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Relationship between meteorological factors and grass growth in spring in the South of Ireland
C. Hurtado-Uria, D. Hennessy, L. Shalloo, Luc Delaby, D. O Connor
To cite this version:
C. Hurtado-Uria, D. Hennessy, L. Shalloo, Luc Delaby, D. O Connor. Relationship between meteoro- logical factors and grass growth in spring in the South of Ireland. Agricultural Research Forum, Mar 2012, Tullamore, Ireland. �hal-02749551�
Relationship between meteorological factors and grass growth in spring in the south of Ireland
C. Hurtado-Uria1, 2, D. Hennessy1, L. Shalloo1, L.
Delaby3 and D. O Connor2
1Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork; 2Cork Institute of Technology, Bishopstown, Cork; 3INRA, UMR 1080, Production du Lait, 35590 St. Gilles, France
Introduction
Ireland has conditions that favour grass growth throughout most of the year, with a 300 day grazing season achieved in the south, providing a competitive advantage in offering a cheap feed source to beef and dairy cattle. Grass growth is highly seasonal with little growth over the winter period due to low temperatures and low levels of solar radiation. Peak grass growth occurs in late spring and early summer, followed by a decline in the late summer and autumn. The climate in Ireland is influenced by the westerly winds and the proximity of the ocean, resulting in a temperate humid climate. Meteorological conditions influence grass growth over the course of the growing season, particularly radiation, temperature and rainfall (Burke et al. 2004), as a result there are variations in grass growth within and between years. The objectives of the study were to determine the meteorological factors having the greatest influence on growth of perennial ryegrass (Lolium perenne L.) in spring from 1982 to 2010 at Teagasc Moorepark.
Material and Methods
Daily data for the spring period from 1982 to 2010 at Teagasc Moorepark (January to April, weeks 1 to 17, 300 observations) were converted into average weekly data. The meteorological data analysed included minimum, maximum and mean air temperatures (°C), soil temperatures at 50 and 100 mm (°C), sunshine hours (h), solar radiation (MJ/m2), rainfall (mm), calculated evapotranspiration (ET) with Hargreaves’s formula (mm) and calculated day length (h). Weekly grass growth was measured using the methodology described by Corral and Fenlon (1978). A regression analysis of weekly meteorological factors and weekly grass growth rates was performed in SPSS with the meteorological factors as the independent variables and grass growth as the dependent variable. The stepwise
option was chosen to enter the significant variables at the 5% level and to remove at the 1% level. Data was also used to investigate the start date of grass growth;
grass growth was considered to have actively commenced when it was 10 kg DM/ha/day.
Table 1. Regression analysis results of weekly meteorological variables and weekly grass growth.
Variable B t F test R2 Error
ET 35.32 13.41
235.09 0.70 17.54 Soil temp 100 mm 7.90 7.14
Max air temp -4.74 -4.02
B is the unstandardized coefficients of the variables t and F are significant at the 0.001 level (***) Results and Discussion
The meteorological factors having the greatest effect on spring grass growth were ET, soil temperature at 100 mm and maximum air temperature with an R2 of 0.70 (Table 1). The three variables showed a positive relationship with grass growth (Figure 1). Temperature affects many physiological and growth functions of perennial ryegrass, including photosynthesis, respiration, spring growth, heading date and senescence.
It took an average of 64 days from 1st January for grass growth rates to reach 10 kg DM/ha/day or greater over the 29 years; the maximum number of days required were 113 days in 1986, and the minimum was 36 days in 2008. Grass growth occurs provided soil temperatures are not lower than 5°C.
Conclusions
Evapotranspiration, soil temperature at 100 mm and maximum air temperature were the factors with the greatest influence on grass growth at Moorepark in the January to April period over the years 1982 to 2010.
References
Corral, A. J. & Fenlon, J. S. (1978). Journal of Agricultural Science 91: 61-67
Burke, J.I., Brereton, A.J., O’Kiely, P. and Schulte, R.P.
(2004). Chapter 7: Weather and crop production in:
Keane, T. and Collins. J. F. (ed.), Climate, Weather and Agriculture, 2nd edition. AGMET, Meteorological Service, Dublin, pp. 161-210.
y = 9.729x - 67.98 R2 = 0.467
0 20 40 60 80 100 120 140
0 5 10 15 20
Maximum air temperature (ºC)
Grass growth (kg DM/ha/day) y = 10.848x - 38.63
R2 = 0.519
0 20 40 60 80 100 120 140
0 5 10 15 20
Soil temperature 100 mm (ºC)
Grass growth (kg DM/ha/day)
y = 41.242x - 24.91 R2 = 0.647 0
20 40 60 80 100 120 140
0 1 2 3 4 5
Evapotranspiration (mm)
Grass growth (kg DM/ha/day)
Figure 1. Relationship between grass growth and maximum air temperature, soil temperature at 100 mm and evapotranspiration in spring at Moorepark from 1982 to 2010.
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